The object of this project is to delineate the mechanisms of stimulation of B and T lymphocytes by an analysis of mitogen-membrane interactions. We have extended our prior studies to determine the major lectin acceptors on human normal and malignant lymphocytes. The chemical modification of certain mitogens has been found to have profound effects on their B and T cell specificity. Biochemical and amino acid sequence analysis of the immune response associated (Ia) antigens of the guinea pig have been initiated to elucidate their role in the control of the immune response. Preliminary data suggest that the smaller polypeptide chain (Ia-L) of these antigens is coded by genes within the I region. Furthermore, the data also suggest that each locus within a strain carries a different gene for this polypeptide chain. BIBLIOGRAPHIC REFERENCES: Janossy, G., Gomez de la Concho, E., Luguetti, A., Snajdr, M.J., Waxdal, M. J. and Platts-Mills, T.: T cell regulation of immunoglobulin synthesis and proliferation in pokeweed (Pa-1) stimulated human lymphocyte cultures. Scand. J. Immunol. 6: 109, 1977. Basham, T.Y. and Waxdal, M.J.: Crosslinking of T cell mitogens: Effects on B and T cell proliferation and immunoglobulin synthesis. J. Immunol. 118: 863, 1977.